EP3565865B1 - (meth)acrylatcopolymere als rheologische additive in bohrflüssigkeiten und bohrflüssigkeiten mit solchen copolymeren - Google Patents

(meth)acrylatcopolymere als rheologische additive in bohrflüssigkeiten und bohrflüssigkeiten mit solchen copolymeren Download PDF

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EP3565865B1
EP3565865B1 EP17822237.8A EP17822237A EP3565865B1 EP 3565865 B1 EP3565865 B1 EP 3565865B1 EP 17822237 A EP17822237 A EP 17822237A EP 3565865 B1 EP3565865 B1 EP 3565865B1
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meth
group
copolymer
drilling fluid
mole
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French (fr)
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EP3565865A1 (de
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René NAGELSDIEK
Alan Steinmetz
Justin Adams
Dominika Bernert
Jasmin RUDNER
George Mark Zody
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BYK Chemie GmbH
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BYK Chemie GmbH
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    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K8/00—Compositions for drilling of boreholes or wells; Compositions for treating boreholes or wells, e.g. for completion or for remedial operations
    • C09K8/02—Well-drilling compositions
    • C09K8/32—Non-aqueous well-drilling compositions, e.g. oil-based
    • C09K8/36—Water-in-oil emulsions
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters

Definitions

  • the invention relates to a drilling fluid in the form of a water-in-oil (W/O) emulsion comprising at least components (A) to (D), wherein component (D) is at least one (meth)acrylic copolymer, which contains at least one of structural units (D1), (D2) and (D3) to introduce at least one hydroxyl and/or amino functionality into the copolymer and which further contains at least one structural unit (D4), a use of said(meth)acrylic copolymer as rheological agent in drilling fluids, which are water-in-oil (W/O) emulsions, as well as to a method of producing oil and/or natural gas or of preparing the production thereof comprising the step of using the inventive drilling fluid for generating and/or operating a drill hole.
  • W/O water-in-oil
  • US patent no. 7,449,430 relates to water-based drilling fluids and discloses the use of non-functional styrene-acrylate or styrene-butadiene based copolymers as fluid loss reducers.
  • US patent no. 7,351,681 is directed at a well bore servicing fluid such as a drilling fluid comprising an ionic water-soluble, hydrophobically modified polymer.
  • U.S. patent no. 6,861,393 discloses non-functional polyalkyl methacrylate polymers as additives for reducing sag in oil-based drilling fluids.
  • Non-functional, styrene-based (co)polymers for use as rheological agents in oil-based drilling fluids are disclosed in WO 2014/009408 A1 .
  • US patent no. 5,629,270 discloses an oil-based drilling fluid, which inter alia contains a non-sulfonated polystyrene.
  • US patent no. 7,285,515 is directed at oil-based drilling fluids, which inter alia contain fluid loss polyacrylate additives.
  • 3,506,574 discloses an oil-based drilling fluid, which contains a graft copolymer of at least one (meth)acrylate, wherein N-vinyl pyrrolidone is grafted on the backbone of said copolymer.
  • (meth)acrylic copolymers which may but do not necessarily have to contain carboxylic acid functionalities, in oil-based drilling fluids is disclosed in WO 00/78891 A1 .
  • the copolymers according to WO 00/78891 A1 are not used as rheological agents, but are used as fluid loss additives.
  • US patent no. 4,548,982 discloses water loss additives for drilling fluids, which are ammonia salts of copolymers of (meth)acrylic acid and at least one of (meth)acrylic acid esters and vinyl esters of saturated monocarboxylic acids having 1 to 3 carbon atoms.
  • the known polymeric additives for incorporation into oil-based drilling fluids are not able, to provide sufficient rheological properties of the drilling fluids. This is in particular the case, since the desire for offshore drilling is still increasing, which results in a need for a rheological additive that can provide a flat rheological profile as the drilling fluid experiences extreme and abrupt changes in temperature as it passes from the ocean and through the earth.
  • a first subject-matter of the present invention is thus a drilling fluid in the form of a water-in-oil (W/O) emulsion comprising at least components (A) to (D), each being different from one another, namely
  • the inventive drilling fluid further comprises at least one oligomer, in particular at least one dimer and/or trimer, of at least one C 10 -C 28 fatty acid as an additional component (E).
  • a further subject-matter of the present invention is a use of at least one (meth)acrylic copolymer as rheological additive in a drilling fluid, wherein the drilling fluid is a water-in-oil (W/O) emulsion and wherein the (meth)acrylic copolymer contains at least one of structural units (D1), (D2) and (D3), which are different from one another,
  • W/O water-in-oil
  • the (meth)acrylic copolymer is used in combination with at least one organic acid, in particular with at least one C 10 -C 28 fatty acid and/or with a oligomer, such as a dimer and/or trimer, thereof, as rheological agent.
  • a oligomer such as a dimer and/or trimer, thereof, as rheological agent.
  • a further subject-matter of the present invention is a method of producing oil and/or natural gas or of preparing the production of oil and/or natural gas, comprising the step of using an inventive drilling fluid for generating and/or operating a drill hole.
  • inventively used copolymer is able to function as rheological agent in drilling fluids such as in the inventive drilling fluids.
  • inventively used copolymer by incorporation of the inventively used copolymer in such drilling fluids, a flat rheology profile of the drilling fluid can be achieved, i.e. it has been observed that the inventively used copolymers impart a constant rheology over a broad range of temperatures, specifically in the range of 40°F and 150°F (i.e. in the range of 4.4°C to 65.5°C).
  • a constant viscosity profile over the whole application range such as in the range of 40°F and 150°F (i.e.
  • inventive drilling fluids in the range of 4.4°C to 65.5°C
  • inventively used (meth)acrylic copolymer contained therein This is in particular the case when an inventively used (meth)acrylic copolymer is used in combination with at least one oligomer, in particular at least one dimer and/or trimer of at least one C 10 -C 28 fatty acid.
  • the inventively used copolymer is able to provide a high flexibility and easy-to-handle properties due to its tunable architecture with respect to the use of structural units (D1) to (D4) and their amounts present in the copolymer.
  • drilling fluid in some passages also referred to as "drilling mud".
  • drilling mud a drilling fluid in general contains a continuous phase and a discontinuous phase (dispersed phase).
  • the inventive drilling fluid is present in the form of a water-in-oil (W/O) emulsion, i.e. is a (W/O) emulsion (invert emulsion).
  • W/O water-in-oil
  • invert emulsion invert emulsion
  • the inventive drilling fluid contains at least one hydrocarbon as continuous phase (component (A)).
  • the at least one hydrocarbon is preferably used as solvent/organic fluid component of the continuous phase.
  • the least one hydrocarbon is a C 10 to C 100 hydrocarbon.
  • Suitable hydrocarbons that can be used as component (A) are aliphatic hydrocarbons, aromatic hydrocarbons and/or araliphatic hydrocarbons.
  • "Araliphatic" hydrocarbons in the sense of the present invention are hydrocarbons that contain both aliphatic and aromatic segments. Aliphatic hydrocarbons such as aliphatic C 10 to C 100 hydrocarbons as well as the aliphatic segments of araliphatic C 10 to C 100 hydrocarbons can be saturated or at least mono-unsaturated.
  • the term "aliphatic” includes both cyclic and non-cyclic residues. Particularly preferred are aliphatic hydrocarbons.
  • component (A) is essentially free of aromatic hydrocarbons.
  • hydrocarbons that can be used as component (A) are diesel oils, mineral oils, kerosene, fuel oils, white oils, synthetic oils, crude oils, synthetic paraffins and olefins.
  • suitable hydrocarbons are Estegreen (Chevron), Ecoflow (Chevron), Saraline (Shell MDS), Mosspar H (PetroSA), Sarapar (Shell MDS), Baroid Alkane (Halliburton), XP-07 (Halliburton), Inteq (Baker Hughes Drilling Fluids), Novadrill (M-I Swaco), Biobase (Shrieve Chemicals), Sasol C1316 paraffin (Sasol), Isoteq (Baker Hughes Drilling Fluids), Amodrill (BP Chemicals), Petrofree Ester (Halliburton), Finagreen Ester (Fina Oil and Chemical), CPChem internal olefins (ChevronPhillips Chemical), and Neoflo olefins (
  • Non-limiting examples include Escaid (Exxon), Vassa LP (Vassa), EDC-95-11 (Total), EDC99-DW (Total), HDF-2000 (Total), Mentor (Exxon), LVT (ConocoPhillips), HDF (Total), BP 83HF (BP), DMF 120HF (Fina), DF-1 (Total), EMO 4000, Shellsol DMA (Shell), IPAR 35 LV (PetroCanada), IPAR 35 (PetroCanada), Telura 401 (Exxon), SIPDRILL (SIP Ltd.), Puredrill® IA35LV, white oil (Ametek; Paoli, Pa.), and Clairsol (Carless Solvents).
  • Additional examples include, but are not limited to, crude oil, diesel oil, Ametek® (Ametek; Paoli, Pa.), Isomerized Alpha Olefin C16 (Chevron Phillips Chemical Company), Isomerized Alpha Olefin C18 (Chevron Phillips Chemical Company), Isomerized Alpha Olefin C16-18 (65:35) (Chevron Phillips Chemical Company), and kerosene.
  • aromatic hydrocarbons can be used, like toluene, xylenes and/or trimethylbenzenes.
  • An exemplary commercial product that is based on aromatic hydrocarbons is Shellsol® A by the company Overlack AG, Germany.
  • Shellsol® A by the company Overlack AG, Germany.
  • the use of aromatic hydrocarbons is not preferred due to their (eco)toxic profile.
  • component (A) is, preferably selected from environmentally benign hydrocarbons, meaning that component (A) is one which, over a reasonable course of time, will biodegrade into relatively harmless materials. Oils of this type are known for use in drilling fluids and similar applications, and are commonly hydrotreated light distillate. The resultant product contains minimal, if any, quantities of aromatic components, and mostly short chain hydrocarbons.
  • the LVT® oil of Calumet Penrico, LLC, and the Low Toxicity Drilling Mud Oil of ExxonMobil, such as those based on ESCAIDTM fluids, are commercial examples of such products.
  • Synthesized biodegradable oils based on alpha or internal olefins or the like are also acceptable for use as component (A), such as AMODRILL® olefin fluids by INEOS USA, LLC, as well as ODC® high purity hydrocarbons of Sasol North America, Inc.
  • Exemplary commercial products that can be used as suitable hydrocarbons for providing the continuous phase are, e.g., the commercial products Amodrill® 1000 (from Ineos), LVT 200 (from DeltaDrilling), and Halliburton XP-07.
  • Amodrill® 1000 is particularly preferred.
  • Amodrill® 1000 is a mixture of C 16 /C 18 olefins.
  • the use of olefins as component (A) is in particular preferred.
  • the continuous phase may additionally contain at least one further component, preferably a component that is miscible with the at least one hydrocarbon used as component (A).
  • at least one further component is preferably an organic solvent such as an organic solvent selected from the group consisting of aliphatic alcohols, aromatic alcohols, araliphatic alcohols, esters, ethers, glycols, glycol ethers, dialkylcarbonates and/or alkylene carbonates.
  • the inventive drilling fluid comprises the at least one hydrocarbon as continuous phase as component (A) in an amount of from 10 to 60 wt.-%, more preferably of from 12.5 to 55 wt.-%, even more preferably of from 15 to 50 wt.-%, still more preferably of from 17.5 to 45 wt.-%, in particular of from 20 to 40 wt.-%, in each case based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • the amount of component (A) in the inventive drilling fluid is higher than the amount of component (B), more preferably is at least times 1.5, even more preferably is at least twice, the amount of component (B) in the drilling fluid, in each case with respect to wt.-%.
  • the inventive drilling fluid contains water or an aqueous solution of at least one organic and/or inorganic salt as discontinuous phase (component (B)).
  • component (B) An example of an aqueous solution of at least one organic and/or inorganic salt known to a person skilled in the art is a brine. Depending on the type of salt dissolved, different types of brine are existent. Examples of suitable components (B) are formation brines and seawater.
  • the organic and/or inorganic salt, which can be present in component (B) is preferably used to control the osmotic pressure of the drilling fluid as needed, e.g. according to drilling conditions.
  • the inventive drilling fluid containing water or an aqueous solution of at least one organic and/or inorganic salt as discontinuous phase as component (B) may further contain suitable hygroscopic materials such as glycols, glycerols and mixtures thereof.
  • suitable hygroscopic materials such as glycols, glycerols and mixtures thereof.
  • an aqueous solution of at least one organic and/or inorganic salt, more preferably of at least one inorganic salt, is used as discontinuous phase.
  • Organic and/or inorganic salts that can be used are organic and/or inorganic salts that are selected from the group consisting of halides, carbonates, sulphates, phosphates, formates, acetates, citrates, lactates, malates, tartrates, hydroxides and mixtures thereof of at least one alkaline metal, at least one alkaline earth metal, at least one metal of the third main group and/or or at least one transition group metal of the periodic system of the elements.
  • Particularly preferred organic and/or inorganic salts are those of the alkaline metals and alkaline earth metals as well as those of the third main group metals and zinc.
  • Especially preferred organic and/or inorganic salts are those of the main groups 1 and 2, mostly preferred are respective salts of Li, Na, K, Cs, Mg and Ca.
  • Preferred anions in each case are halides, carbonates, sulphates, phosphates, formates and/or hydroxides.
  • Especially preferred anions in each case are chlorides, bromides, and iodides.
  • Most preferred salts are NaCl, KCl, NaBr, and/or CaCl 2 .
  • the inventively used aqueous solution of at least one organic and/or inorganic salt preferably contains the at least one organic and/or inorganic salt in an amount of 0.1 to 40 wt.-%, more preferably of 5 to 35 wt.-%, even more preferably of 10 to 30 wt.-%, in particular of 15 to 25 wt.-%, in each based on the total weight of the solution.
  • inventively used aqueous solution of at least one organic and/or inorganic salt may additionally contain at least one further water-miscible organic compound, which is different from the organic salt that may be contained in the inventively used aqueous solution.
  • the inventive drilling fluid comprises component (B) in an amount of from 2.5 to 40 wt.-%, more preferably of from 5 to 35 wt.-%, even more preferably of from 5 to 30 wt.-%, still more preferably of from 10 to 25 wt.-%, in particular of from 10 to 20 wt.-%, in each case based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • the inventive drilling fluid contains at least one weighting agent as component (C).
  • the weighting agent is used in order to enhance the density of the inventive drilling fluid and to serve as a filler.
  • Weighting materials agents that can be used as component (C) include such materials as calcium carbonate, silicates, clays, barites, specular hematite, iron ores, siderite, ilmenite, galena, and mixtures thereof. Weighting agents can be used to balance or adjust drilling fluid density and/or hydrostatic pressure, such as downhole pressure, to prevent fluids from entering the wellbore from the geological formation.
  • the inventive drilling mud contains at least one weighting agent selected from the group consisting of galena, hematite, magnetite, iron oxides, illmenite, barite (BaSO 4 ), siderite, celestite, dolomite, calcite and combinations thereof. Barite is in particular preferred.
  • the inventive drilling fluid comprises component (C) in an amount of from 10 to 90 wt.-%, more preferably of from 15 to 85 wt.-%, even more preferably of from 20 to 80 wt.-%, still more preferably of from 30 to 70 wt.-%, in particular of from 40 to 60 wt.-%, in each case based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • (meth)acrylic copolymer as component of the drilling fluid is also named an “inventively used copolymer” or simply “component (D)”.
  • (meth)acrylic means “acrylic” and/or "methacrylic”.
  • (meth)acrylate means acrylate and/or methacrylate. Therefore, a “(meth)acrylic copolymer” in general may be formed from only “acrylic monomers”, only “methacrylic monomers” or from both "acrylic and methacrylic monomers”. However, ethylenically unsaturated monomers other than acrylic and/or methacrylic monomers as e.g. styrene and the like may also be additionally contained in a "(meth)acrylic copolymer".
  • a (meth)acrylic copolymer may consist of only acrylic and/or methacrylic monomer units but does not have to.
  • the backbone of the (meth)acrylic copolymer is formed from more than 50 mole-%, even more preferably of from more than 75 mole-% of (meth)acrylic monomers.
  • the inventively used (meth)acrylic copolymer has a weight average molecular weight (M w ) in the range of from 1,000 to 200,000 g/mol, more preferably of from 2,000 to 190,000 g/mol, even more preferably of from 5,000 to 180,000 g/mol, still more preferably of from 10,000 to 170,000 g/mol, yet more preferably of from 15,000 to 160,000 g/mol, in particular of from 20,000 to 150,000 g/mol.
  • M w weight average molecular weight
  • the inventively used (meth)acrylic copolymer has a weight average molecular weight (M w ) in the range of from 10,000 to 100,000 g/mol, more preferably of from 20,000 to 80,000 g/mol, even more preferably of from 30,000 to 70,000 g/mol, still more preferably of from 40,000 to 60,000 g/mol.
  • the inventively used (meth)acrylic copolymer has a weight average molecular weight (M w ) in the range of from 25,000 to 150,000 g/mol, more preferably of from 35,000 to 130,000 g/mol, even more preferably of from 45,000 to 110,000 g/mol, still more preferably of from 60,000 to 100,000 g/mol.
  • the inventively used (meth)acrylic copolymer has a weight average molecular weight (M w ) in the range of from 50,000 to 200,000 g/mol, more preferably of from 60,000 to 180,000 g/mol, even more preferably of from 70,000 to 160,000 g/mol, still more preferably of from 80,000 to 155,000 g/mol, in particular of from 100,000 to 150,000 g/mol.
  • M w weight average molecular weight
  • the weight average molecular weight of the inventively used copolymers is determined according to the method described hereinafter ("Test methods"), i.e. is determined via GPC using polystyrene standards and THF as eluent.
  • the inventively used copolymers preferably have a polydispersity P (M w /M n ) of >1.0, more preferably of >1.2, even more preferably of >1.3, still more preferably of >1.4, yet more preferably of >2.0, in particular of >2.3 and most preferred of >2.5.
  • the upper limit is in each case preferably a polydispersity P of 15.0, more preferably a polydispersity P of 10.0.
  • M n is the number average molecular weight of the inventively used copolymers and can be determined according to the same method, which is also used for determining their weight average molecular weight.
  • the inventively used copolymers have a polydispersity P in the range of from >1.0 to 15.0 such as of from 1.02 to 15.0, more preferably of from 1.2 to 10.0, even more preferably of from 1.3 to 9.0, still more preferably of from 1.5 to 8.8, yet more preferably of from 1.7 to 8.6, even more preferably of from 2.0 to 9.4, in particular of from 2.4 to 9.0 and most preferred of from 2.8 to 8.5.
  • the inventively used copolymer is a non-ionic copolymer, e.g. does not contain any ionic groups such as ammonium salt groups as, e.g., the polymers disclosed in US patent no. 4,548,982 .
  • the inventively used (meth)acrylic copolymer does not contain any acid groups, in particular does not contain any carboxylic acid groups, neither in the free form nor in the form of a salt.
  • the structural units (D1), (D2) and (D3) and (D4) contains such an acid group.
  • the inventively used (meth)acrylic copolymer (D) contains at least one of structural units (D1), (D2) and (D3), which are different from one another,
  • the inventively used (meth)acrylic copolymer contains at least one of structural units (D1) and (D2).
  • the copolymer preferably has an OH number in the range of from 5 to 150 mg KOH/g, more preferably of from 10 to 100 mg KOH/g, in particular of from >10 to 70 mg KOH/g.
  • the copolymer preferably has an amine number in the range of from 5 to 200 mg KOH/g, more preferably of from 10 to 150 mg KOH/g, in particular of from >10 to 125 mg KOH/g.
  • the OH numbers are theoretical values determined by calculation based on the copolymer as such and on the molar ratios of the respective monomers used for its preparation. The same applies to the amine numbers.
  • the at least one amino group present in structural units (D2) and/or (D3) can be a primary, secondary or tertiary amino group. It is possible that one of structural units (D2) and (D3) contains, e.g., different types of amino groups such as one secondary and one tertiary amino group. It is, of course, also possible that each of structural units (D2) and (D3) contains the same type of amino groups such as tertiary amino groups only. Preferably, the at least one amino group present in structural units (D2) and/or (D3) is a tertiary amino group.
  • the relative molar ratio of the at least one of structural units (D1), (D2) and (D3) to the at least one structural unit (D4) in the (meth)acrylic copolymer is in the range of from 1:40 to 1.5:1, more preferably in the range of from 1:35 to 1.5:1, even more preferably in the range of from 1:30 to 1:1, still more preferably in the range of from 1:27.5 to 1:1.5.
  • the amount of structural units (D4) in the (meth)acrylic copolymer is at least 40 mole-% more preferably at least 45 mole-%, even more preferably at least 50 mole-% or at least 55 mole-%, still more preferably at least 60 mole-% or at least 65 mole-%, yet more preferably at least 70 mole-%, in particular at least 80 mole-%, most preferably at least 85 mole-%, in each case based on the total amount of all structural units of the copolymer.
  • the amount of at least one of structural units (D1), (D2) and (D3) in the (meth)acrylic copolymer is at least 1 mole-%, more preferably at least 3 mole-%, even more preferably at least 5 mole-%, in particular at least 7 mole-% and most preferably at least 8 mole-%, in each case based on the total amount of structural units of the copolymer.
  • the amount of at least one of structural units (D1), (D2) and (D3) in the (meth)acrylic copolymer is at most 60 mole-%, more preferably at most 50 mole-%, even more preferably at most 40 mole-% or at most 30 mole-%, still more preferably at most 25 mole-% in particular at most 20 mole-% and most preferably at most 15 mole-%, in each case based on the total amount of all structural units of the copolymer.
  • the amount of monomers used for incorporation of structural unit (D4) into the (meth)acrylic copolymer is at least 40 mole-% more preferably at least 45 mole-%, even more preferably at least 50 mole-% or at least 55 mole-%, still more preferably at least 60 mole-% or at least 65 mole-%, yet more preferably at least 70 mole-%, in particular at least 80 mole-%, wherein the sum of all monomers used for preparing the (meth)acrylic copolymer adds up to 100 mole-%.
  • Suitable monomers for incorporation of structural unit (D4) into the (meth)acrylic copolymer are, e.g., the monomers (d4) as specified hereinafter.
  • Radical R denotes a C 4 -C 25 aliphatic residue, an aromatic C 6 -C 25 residue or an araliphatic C 7 -C 25 residue.
  • C 4 -C 25 aliphatic residue refers in the sense of the present invention to an aliphatic residue having a total of 4 to 25 carbon atoms.
  • a preferred “C 4 -C 25 aliphatic residue” is a "C 8 -C 25 aliphatic residue” having a total of 8 to 25 carbon atoms.
  • Another preferred “C 4 -C 25 aliphatic residue” is a "C 4 -C 22 aliphatic residue” having a total of 4 to 22 carbon atoms. More preferred is a "C 8 -C 18 aliphatic residue” having a total of 8 to 18 carbon atoms.
  • C 8 -C 14 aliphatic residue having a total of 8 to 14 carbon atoms.
  • the respective aliphatic residue can be unsaturated or saturated, but preferably is saturated. Further, the respective aliphatic residue can be branched or unbranched (linear).
  • the term "aliphatic” includes in each case both cyclic and non-cyclic residues, but preferably only means non-cyclic residues.
  • C 6 -C 25 aromatic residue refers in the sense of the present invention to an aromatic residue having a total of 6 to 25 carbon atoms.
  • a preferred “C 6 -C 25 aromatic residue” is a “C 6 -C 20 aromatic residue” having a total of 6 to 20 carbon atoms. More preferred is a “C 6 -C 14 aromatic residue” having a total of 6 to 14 carbon atoms.
  • C 7 -C 25 araliphatic residue refers in the sense of the present invention to an araliphatic residue having a total of 7 to 25 carbon atoms.
  • a preferred "C 7 -C 25 a araliphatic residue” is a "C 7 -C 20 araliphatic residue” having a total of 7 to 20 carbon atoms. More preferred is a "C 7 -C 14 araliphatic residue” having a total of 7 to 14 carbon atoms.
  • Araliphatic residues in the sense of the present invention contain both aliphatic and aromatic segments.
  • the term “aliphatic” again includes both cyclic and non-cyclic residues, preferably only non-cyclic residues.
  • radical R denotes a C 4 -C 25 aliphatic residue, more preferably a C 8 -C25 aliphatic residue or a C 4 -C 22 aliphatic residue, or an araliphatic C 7 -C 25 residue, more preferably a C 6 -C 20 araliphatic residue.
  • radical R denotes a C 8 -C 25 aliphatic residue or a C 4 -C 22 aliphatic residue or a C 8 -C 18 aliphatic residue or a C 8 -C 22 aliphatic residue or a C 8 -C 14 aliphatic residue or a C 4 -C 14 aliphatic residue.
  • the polymerization reaction for preparing the inventively used copolymer can be carried out by all methods known in literature, such as free radical polymerization, controlled/living radical polymerization, ionic polymerization, or group transfer polymerization. It is well-known that the average molecular weight and its distribution of an inventively used copolymer can be controlled by using chain transfer agents or making use of controlled/living polymerization technologies. Branched or star shaped structures are available for example by using difunctional or higher functional co-monomers during the copolymerization and/or the use of multifunctional initiators and/or multifunctional chain transfer agents. Free radical polymerization is preferred. At least two ethylenically unsaturated monomers different from one another are preferably used, which each contain at least one, preferably precisely one, terminal ethylenically unsaturated group.
  • the inventively used copolymer is a random copolymer or structured copolymer.
  • Structured copolymers are e.g. block copolymers such as linear block copolymers, branched block copolymers, star-shaped block copolymers, gradient copolymers and comb copolymers.
  • the inventively used copolymer may have a random, or gradient-like or block-like sequence of copolymerized structural units derived from suitable ethylenically unsaturated monomers.
  • the inventively used copolymer has a random sequence of copolymerized structural units.
  • the structure of the inventively used copolymer is preferably linear or branched.
  • inventively used copolymer has a gradient-like or block-like sequence of copolymerized structural units.
  • Gradient copolymers are preferably copolymers, in which, along the polymer chains, the concentration of structural units of a particular ethylenically unsaturated monomer or the structural units of a mixture of ethylenically unsaturated monomers decreases continuously and the concentration of structural units of a different ethylenically saturated monomer or of structural units of a mixture of different ethylenically unsaturated monomers increases.
  • the term "gradient copolymer" is known to those skilled in the art. Thus for example gradient copolymers are disclosed in EP 1 416 019 A1 and in WO 01/44389 A1 .
  • Block copolymers are copolymers obtained by adding at least two different ethylenically unsaturated monomers, two different mixtures of ethylenically unsaturated monomers or by adding an ethylenically unsaturated monomer and a mixture of ethylenically unsaturated monomers at different times in the practice of a controlled polymerization, wherein an ethylenically unsaturated monomer or a mixture of ethylenically unsaturated monomers is initially charged at the start of the reaction.
  • block copolymers may have at least one transition in their structural units along the polymer chain, said transition marking the boundary between the individual blocks.
  • Suitable block copolymer structures are e.g. AB diblock copolymers, ABA triblock copolymers or ABC triblock copolymers.
  • Block copolymers which are preferably used according to the present invention, contain blocks having a minimum number of 3 structural units per block.
  • the minimum number of structural units per block is preferably 3, more preferably 5 and most preferably 10.
  • Each of the blocks may contain the same structural units, but each in different numbers, or is constructed of different structural units.
  • the inventively used copolymer has a block structure, it preferably is of the type A-B, A-B-A, B-A-B, A-B-C and/or A-C-B, in which the A, B and C blocks represent a differing composition of structural units, wherein the blocks A, B and C differ in their respective composition of structural units and/or wherein the amount of structural units in two adjacent blocks differs from each other by more than 5% by weight in each case.
  • the (meth)acrylic copolymer as component (D) is obtainable by copolymerization of at least one of monomers (d1), (d2) and (d3), namely
  • monomers (d1), (d2), (d3), (d4) as well as (d5), (d6) and (d7) are different from each other.
  • Monomers (d1) which can be used for preparing structural unit (D1), are preferably defined as above, i.e. as ethylenically unsaturated monomers having at least one hydroxyl group or at least one functional group that can be transformed into a hydroxyl group by a polymer analogous reaction after formation of the copolymer.
  • monomer (d1) already contains at least one hydroxyl group.
  • Monomers (d2) which can be used for preparing structural unit (D2), are preferably defined as above, i.e. as ethylenically unsaturated monomers having at least one amino group or at least one functional group that can be transformed into an amino group by a polymer analogous reaction after formation of the copolymer.
  • monomer (d2) already contains at least one amino group.
  • Monomers (d3) which can be used for preparing structural unit (D3), are preferably defined as above, i.e. as ethylenically unsaturated monomers having at least one amino group or at least one functional group that can be transformed into an amino group by a polymer analogous reaction after formation of the copolymer and having at least one hydroxyl group or at least one functional group that can be transformed into a hydroxyl group by a polymer analogous reaction after formation of the copolymer.
  • the at least one functional group, that can be transformed into a hydroxyl group by a polymer analogous reaction after formation of the copolymer, and the at least one functional group, that can be transformed into an amino group by a polymer analogous reaction after formation of the copolymer, are identical.
  • one single functional group may be transformed into both a hydroxyl group and an amino group by a polymer analogous reaction after formation of the polymer.
  • an epoxide group containing ethylenically unsaturated monomer such as glycidyl (meth)acrylate may be used for preparing a precursor structural unit (D3) of the copolymer.
  • said epoxide group may then be transformed by reaction with a primary or secondary amine into a structural unit (D3) containing both a hydroxyl group and an amino group.
  • Monomers (d4) can be used for preparing structural unit (D4)
  • monomers (d5) can be used for preparing optional structural unit (D5)
  • monomers (d6) can be used for preparing optional structural unit (D6)
  • monomers (d7) can be used for preparing optional structural unit (D7).
  • monomers (d1) are (meth)acrylate and/or (meth)acrylamide momomers, in particular (meth)acrylate monomers.
  • Examples of monomers (d1) are 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, 4-hydroxybutyl methacrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, glycerol mono (meth)acrylate, N-(2-hydroxypropyl) (meth)acrylamide, allyl alcohol, hydroxystyrene, hydroxyalkyl vinyl ethers such as hydroxybutyl vinyl ether and vinylbenzyl alcohol. Further examples of monomers (d1) are alkoxylated derivatives of these monomers.
  • monomers (d1) are derivatives thereof, which are obtainable by reaction with oxetanes.
  • Other examples of monomers (d1) are such monomers, which can be obtained by ring-opening polymerization of lactones using the hydroxyl functional monomers named before as starter: in this case preferred lactones are gamma-butyrolactone, delta-valerolactone, and epsilon-caprolactone as well as combinations thereof.
  • the hydroxyl functional monomers named before can also undergo a combination of alkoxylation, reaction with oxetanes, and/or lactone ring opening polymerization to yield a mixed polyether/polyester macromonomer with OH functionality, which can be used as monomer (d1).
  • 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxypropyl acrylate and 3-hydroxypropyl methacrylate or mixtures thereof are particularly preferred.
  • Examples of monomers (d2) are N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminopropyl acrylate, N,N-dimethylaminopropyl methacrylate, 2-(N,N-diethylamino)ethyl (meth)acrylate, 2-(N,N-dimethylamino)ethyl (meth)acrylate, N-[3-(N,N-dimethylamino)propyl] (meth)acrylamide, 3-dimethylaminoneopentyl (meth)acrylate, 2-N-morpholinoethyl (meth)acrylate, N-[3-(N,N-dimethylamino)propyl] (meth)acrylamide, 2-(N,N-diethylamino)ethyl (meth)acrylamide, 2-(tert-butylamino)
  • the (meth)acrylate and (meth)acrylamide based monomers (d2) are preferred.
  • (Meth)acrylate monomers are very preferred.
  • Particularly preferred monomers (d2) are N,N-dimethylaminoethyl acrylate, N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminopropyl acrylate and N,N-dimethylaminopropyl methacrylate or mixtures thereof.
  • Examples of monomers (d4), which are (meth)acrylic esters of an aliphatic C 4 -C 25 -monoalcohol are n-butyl acrylate, n-butyl methacrylate, i-butyl acrylate, i-butyl methacrylate, t-butyl acrylate, t-butyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, stearyl acrylate, stearyl methacrylate, behenyl acrylate, behenyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, isobornyl acrylate and isobornyl methacrylate.
  • An example of a monomer (d4), which is a (meth)acrylic ester of an aromatic C 6 -C 25 -monoalcohol is phenyl (meth)acrylate.
  • monomers (d4), which are (meth)acrylic esters of an araliphatic C 4 -C 25 -monoalcohol are benzyl acrylate and benzyl methacrylate.
  • Particularly preferred are (meth)acrylic esters of an aliphatic C 8 -C 25 -monoalcohol, most preferred of an aliphatic C 8 -C 18 -monoalcohol.
  • Preferred monomers are n-butyl acrylate, n-butyl methacrylate, lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate. Most preferred are lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate and 2-ethylhexyl methacrylate.
  • Examples of monomers (d5), which are (meth)acrylic esters of an aliphatic C 1 -C 3 -monoalcohol are methyl acrylate, methyl methacrylate, ethyl acrylate,ethyl methacrylate, n-propyl (meth)acrylate and isopropyl (meth)acrylate.
  • Examples of monomers (d6) are styrene, alpha-alkylstyrenes, especially alphamethylstyrene, and/or vinyltoluene; vinylbenzoic acid (all isomers), alpha-methylvinylbenzoic acid (all isomers), and/or p-vinylbenzenesulfonic acid, maleic and/or fumaric acid and/or itaconic acid and their esters, amides, and imides, and (meth)acrylic acid, nitriles such as acrylonitrile and/or methacrylonitrile and methoxypolyethylene glycol monoacrylate and methoxypolyethylene glycol monomethacrylate as well as methoxypolypropylene glycol monoacrylate and methoxypolypropylene glycol monomethacrylate.
  • monomers containing acid groups are not used as monomers (d6).
  • a particularly preferred monomer (d6) is styrene.
  • Examples of monomers (d7) are divinylbenzene, di(meth)acrylate monomers, tri(meth)acrylate monomers and tetra(meth)acrylate monomers.
  • the (meth)acrylic copolymer as component (D) is obtainable by copolymerization of at least one of monomers (d1), (d2) and (d3), namely
  • the (meth)acrylic copolymer as component (D) is obtainable by copolymerization of at least one of monomers (d1) and (d2), namely
  • the (meth)acrylic copolymer as component (D) is obtainable by copolymerization of at least one of monomers (d1) and (d2), namely
  • the (meth)acrylic copolymer contains 3 to 60 mole-% of at least one of structural units (D1), (D2) and/or (D3), 40 to 97 mole-% of structural units (D4) as well as optionally 0 to 20 mole-% of at least one of structural units (D5) and (D6) as well as optionally 0 to 5 mole-% of structural units (D7), wherein the amounts in mole-% are based in each case on the total amount of all structural units of the copolymer.
  • Structural units (D5) and (D6) can be formed from monomers (d5) and (d6), respectively.
  • Structural unit (D7) can be formed from monomers (d7).
  • the (meth)acrylic copolymer contains 5 to 50 mole-% of at least one of structural units (D1), (D2) and/or (D3), 50 to 95 mole-% of structural units (D4) as well as optionally 0 to 15 mole-% of at least one of structural units (D5) and (D6) as well as optionally 0 to 4 mole-% of structural units (D7), wherein the amounts in mole-% are based in each case on the total amount of all structural units of the copolymer.
  • the (meth)acrylic copolymer contains 7 to 30 mole-% of at least one of structural units (D1), (D2) and/or (D3), 70 to 93 mole-% of structural units (D4) as well as optionally 0 to 10 mole-% of at least one of structural units (D5) and (D6) as well as optionally 0 to 3 mole-% of structural units (D7), wherein the amounts in mole-% are based in each case on the total amount of all structural units of the copolymer.
  • the (meth)acrylic copolymer contains 8 to 25 mole-% of at least one of structural units (D1), (D2) and/or (D3), 75 to 92 mole-% of structural units (D4) as well as optionally 0 to 10 mole-% of at least one of structural units (D5) and (D6) as well as optionally 0 to 2 mole-% of structural units (D7), wherein the amounts in mole-% are based in each case on the total amount of all structural units of the copolymer.
  • Typical reactions for transforming a functional group into a hydroxyl group by a polymer analogous reaction after formation of the copolymer or for transforming a functional group into an amino group by a polymer analogous reaction after formation of the copolymer are (i) the esterification or amidation of (meth)acrylic acid units or maleic anhydride based units or (ii) the transesterification or amidation of (meth)acrylate units with aminoalcohols like N,N-dialkylaminoalkyl alcohols or amines like N,N-dialkylaminoalkyl amines or (iii) the ring opening reaction of an epoxide group like in a glycidyl (meth)acrylate based structural unit, in which a hydroxyl group is formed.
  • the inventively used copolymer functions as rheological agent in the inventive drilling fluids.
  • a flat rheology profile of the drilling fluid can be achieved.
  • Parameters for achieving a flat rheology profile are known to the person skilled in the art and, e.g., named and disclosed in US 2013/0331303 A1 .
  • a "flat rheology profile" in the sense of the present invention preferably means that the inventively used copolymers impart a constant rheology over a broad range of temperatures, specifically in the range of 40°F and 150°F (i.e. in the range of 4.4°C to 65.5°C).
  • the amount of the inventively used copolymer in the inventive drilling fluid is of from 0.005 to 8.0 wt.-% or of from 0.005 to 5.0 wt.-%, more preferably of from 0.075 to 4.0 wt.-%, even more preferably of from 0.01 to 3.0 wt.-%, still more preferably of from 0.015 to 2.5 wt.-%, yet more preferably of from 0.02 to 2.0 wt.-%, in particular of from 0.025 to 1.5 wt.-%, in each based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • the inventive drilling fluid further comprises at least one acid as component (E).
  • Said at least one acid can be an inorganic and/or an organic acid.
  • component (E) is at least one organic acid. More preferably, component (E) is at least one organic C 10 -C 28 fatty acid and/or at least one oligomer of at least one C 10 -C 28 fatty acid.
  • at least one dimer and/or trimer of at least one C 10 -C 28 fatty acid most preferably at least one dimer and/or trimer of at least one C 12 -C 24 fatty acid is used as component (E).
  • the inventively used (meth)acrylic copolymer is used in combination with at least one acid such as at least one oligomer of at least one C 10 -C 28 fatty acid in the inventive drilling fluid.
  • the oligomer of the at least one fatty acid can be saturated or at least mono-unsaturated.
  • aliphatic here embraces preferably acyclic saturated or unsaturated, preferably unsaturated, branched or unbranched aliphatic radicals. Unsaturated aliphatic radicals here have at least one, preferably 1, 2, 3, 4, or 5, more preferably 1, 2, 3, or 4, very preferably 1, 2, or 3 carbon double bond(s).
  • the fatty acids may be natural or synthetically produced fatty acids.
  • Exemplary fatty acids that can be oligomerized are selected from the group consisting of myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nonadecanoic acid, arachidic acid, henicosanoic acid, docosanoic acid, myristoleic acid, palmitoleic acid, petroselinic acid, oleic acid, elaidic acid, vaccenic acid, gadoleic acid, icosenoic acid, cetoleic acid, erucasic acid, linoleic acid such as ⁇ -linoleic acid, linolenic acid such as ⁇ -linolenic acid, calendic acid such as ⁇ -calendic acid and ⁇ -calendic acid, punicic acid, eleostearic acid, arachidonic acid, timnodonic acid, clupanodonic acid, cervonic acid, hexadecat
  • fatty acid encompasses, in the sense of the present invention, preferably also fatty acid derivatives such as corresponding fatty acid esters and/or salts of these fatty acids, for example.
  • At least one dimer and/or trimer (“dimerized and/or trimerized fatty acids") of at least one C 10 -C 28 fatty acid is used as component (E).
  • a dimer can be formed from two identical or from two different fatty acids.
  • a trimer can be formed from identical or different fatty acids.
  • At least one C 10 -C 28 fatty acid has to be used for preparing component (E).
  • At least one aliphatic C 10 -C 28 monocarboxylic acid can be dimerized with (meth)acrylic acid.
  • One preferred example for this is 5-(or 6)-carboxy-4-hexylcyclohex-2-ene-1-octanoic acid, a monocyclic C 21 dicarboxylic acid.
  • Oligomers of fatty acids (“oligomerized fatty acids") including dimers and trimers thereof are known to a person skilled in the art.
  • dimers and/or trimers of any the above named exemplary fatty acids wherein the dimers and trimer can be composed of identical or different fatty acids in each case.
  • dimers and/or trimers of fatty acids selected from the group consisting of linoleic acid, oleic acid, palmitic acid, tall oil fatty acids combinations thereof.
  • a number of oligomers of fatty acids are commercially available.
  • Exemplary commercial products are products of the Empol® series from the company BASF and of the Pripol® series from the company Croda such as Empol® 1003, 1005, 1008, 1012, 1016, 1026, 1028, 1043, 1061 and 1062 and Pripol® 1006, 1009, 1012, 1013, 1017, 1022, 1025, 1027 and 1040.
  • the relative weight ratio of the inventively used (meth)acrylic copolymer and the at least one oligomer of at least one C 10 -C 28 -fatty acid is in the range of from 1:99 to 99:1, more preferably of from 1:9 to 9:1, even more preferably of from 1:7.5 to 1.5:1, still more preferably of from 1:5.5 to 1:1.5, in particular of from 1:4 to 1:2.3.
  • the inventive drilling fluid comprises component (E) in an amount of from 0.005 to 10 wt.-%, more preferably of from 0.0075 to 7.5 wt.-%, even more preferably of from 0.01 to 5 wt.-%, still more preferably of from 0.015 to 2.5 wt.-%, yet more preferably of from 0.02 to 1.5 wt.-%, in particular of from 0.05 to 1 wt.-%, most preferred of from 0.075 to 0.5 wt.-% or of from 0.09 to 0.3 wt.-%, in each case based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • inventive drilling fluid may contain at least one further component.
  • inventive drilling fluid contains at least one further additive selected from the group consisting of thixotropic agents, emulsifiers, alkalinity imparting components, proppants, fluid loss additives, thinners and viscosifiers.
  • the components are different from each other and are also different from any of the components (A), (B), (C), (D) and (E).
  • the inventive drilling mud contains at least one preferably inorganic thixotropic agent.
  • Thixotropic agents which impart thickening and gelling properties, used in drilling fluids may include organophilic phyllosilicates (hereinafter referred to as "organoclays").
  • organoclays used may be any of those which have substantial base-exchange capacity. Examples of such organoclays include bentonite (such as swelling bentonite), montmorillonite, hectorite, attapulgite, illite, Fuller's earth, beidellite, saponite, sepiolite, vermiculite, zeolites, and mixtures thereof. Exemplary materials based on bentonites are available from BYK Additives Inc.
  • the at least one thixotropic agent comprises at least one organoclay of bentonite, montmorillonite, hectorite, attapulgite, illite, Fuller's earth, beidellite, saponite, sepiolite, vermiculite, and/or zeolites.
  • the organoclay may be a coated with at least one of at least one quaternary ammonium compound or at least one phosphonium compound.
  • the inventive drilling fluid comprises at least one preferably inorganic thixotropic agent such as at least one organoclay in an amount of from 0.01 to 10 wt.-%, more preferably of from 0.025 to 7.5 wt.-%, even more preferably of from 0.05 to 5 wt.-%, still more preferably of from 0.075 to 2.5 wt.-%, in particular of from 0.10 to 1.5 wt.-% or of from 0.15 to 1.0 wt.-%, in each case based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • the inventive drilling fluid does not contain any organoclay ("clay free drilling mud").
  • the inventive drilling mud contains at least one emulsifier.
  • Emulsifiers or emulsifier systems may form or stabilize the inventive drilling fluid, and/or may serve as wetting agents for solids.
  • Surfactants may be used in the drilling fluids, for emulsifying the aqueous phase and/or as wetting agents for the solid phase(s), and may include alkali and alkaline earth metal salts of fatty acids, fatty acid derivatives, rosin acids, tall oil acids, or synthetic emulsifiers such as alkyl aromatic sulfonates, aromatic alkyl sulfonates, long chain sulfates, oxidized tall oils, carboxylated 2-alkyl imidazolines, imidazoline salts, amido amines, amide-imidoamines, alkoxy phenols, polyalkoxy alcohols, alkyl phenols, ether carboxylates, lecithins, high molecular weight alcohols, polymer surfactants and the like.
  • the emulsifier is different from the other components, which are present or may be present in the inventive drilling fluid, in particular from components (A), (B), (C), (D) and (E).
  • the inventive drilling fluid comprises at least one emulsifier in an amount of from 0.01 to 10 wt.-%, more preferably of from 0.05 to 8 wt.-%, even more preferably of from 0.1 to 7 wt.-%, still more preferably of from 0.2 to 6 wt.-%, in particular of from 0.5 to 5 wt.-% or of from 1.0 to 4.0 wt.-%, in each case based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • the inventive drilling mud contains at least one component, which imparts alkalinity to the fluid, i.e. which is used as an alkalinity regulator, and which is in particular different from component (b).
  • alkalinity imparting components are selected from oxides, hydroxides, carbonates, hydrogen carbonates of alkali and/or alkaline earth metals or mixtures thereof.
  • a preferred example of an alkalinity imparting component is lime (Ca(OH) 2 ).
  • Other alkalinity regulating additives include caustic soda (NaOH), soda ash (Na 2 CO 3 ), NaHCO 3 , CaO, MgO, and Mg(OH) 2 .
  • the inventive drilling fluid comprises at least one alkalinity imparting compound in an amount of from 0.01 to 10 wt.-%, more preferably of from 0.05 to 8 wt.-%, even more preferably of from 0.1 to 7 wt.-%, still more preferably of from 0.2 to 6 wt.-%, in particular of from 0.3 to 5 wt.-% or of from 0.5 to 3 wt.-%, in each case based on the total weight of the drilling fluid.
  • the total amount of all components present in the drilling fluid adds up to 100 wt.-%.
  • the drilling mud may contain further components like proppants, H 2 S scavengers, fluid loss additives, thinners and viscosifiers; their purpose and typical examples of these components can be found in 'Composition and Properties of Drilling and Completion Fluids' by Ryen Caenn, H.C.H. Darley and George R. Gray, Sixth Editi on as well as in 'Drilling Fluids Engineering Manual' by Newpark Drilling Fluids LLC, Houston/TX, Version 2.0 November 2005 and furthermore in 'Drilling Fluids' by Kate van Dyke, 1st edition / 5th impression 2012, published by Petroleum Extension Service, Austin/TX .
  • proppants H 2 S scavengers
  • fluid loss additives thinners and viscosifiers
  • the inventive drilling fluid comprises
  • the inventive drilling fluid comprises
  • the inventive drilling fluid comprises
  • a further subject-matter of the present invention is a use of the at least one (meth)acrylic copolymer being present as component (D) in the drilling fluid according to the first subject-matter of the present application as rheological additive in a drilling fluid, wherein the drilling fluid is a water-in-oil (W/O) emulsion.
  • W/O water-in-oil
  • a further subject-matter of the present invention is a use of at least one (meth)acrylic copolymer as rheological additive in a drilling fluid, wherein the drilling fluid is a water-in-oil (W/O) emulsion and wherein the (meth)acrylic copolymer contains at least one of structural units (D1), (D2) and (D3), which are different from one another,
  • W/O water-in-oil
  • the inventively used (meth)acrylic copolymer influences the rheology of the drilling fluid when used in oil and/or natural gas drilling operations.
  • the inventively used (meth)acrylic copolymer provides a flat rheology profile of the drilling fluid.
  • a drilling fluid can be provided that has at least one a Yield Point, 10 minute gel value, and 6 RPM value within +/- 20% of the mean values across a temperature range of from from 40 °F to 150 °F (4.4 to 65.5°C).
  • the (meth)acrylic copolymer is used in combination with at least one component (E) as defined hereinbefore as rheological agent. More preferably, the (meth)acrylic copolymer is used in combination with at least one acid such as at least one organic acid, in particular in combination with at least one organic C 10 -C 28 fatty acid and/or at least one oligomer such as a dimer and/or trimer of at least one C 10 -C 28 fatty acid as rheological agent.
  • at least one acid such as at least one organic acid, in particular in combination with at least one organic C 10 -C 28 fatty acid and/or at least one oligomer such as a dimer and/or trimer of at least one C 10 -C 28 fatty acid as rheological agent.
  • inventively used (meth)acrylic copolymer may be combined with at least one component (E) so that the combination of said (meth)acrylic copolymer and component (E) may be added as a single component to the drilling fluid in order to facilitate handling of the materials upon addition to the drilling fluid.
  • a further subject-matter of the present invention is a method of producing oil and/or natural gas or of preparing the production of oil and/or natural gas, comprising the step of using an inventive drilling fluid according for generating and/or operating a drill hole.
  • the weight average (M w ) molecular weights (and the molecular weight distribution as well as the number average molecular weights (M n )) of the inventively used copolymers or any precursors thereof are determined by GPC-analysis (gel permeation chromatography analysis) according to DIN 55672-1:2007-08 at 40°C. Tetrahydrofuran (THF) was used as the eluent with an elution rate of 1 ml/min. In the case of copolymers having amino groups, 1 vol.-% of dibutylamine was added to the THF eluent used. The conventional calibration was carried out using polystyrene standards having molecular weights between 1,000,000 and 162 g/mol.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 70.2 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 75.0 g lauryl methacrylate, 29.2 g 2-ethylhexyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min. After the complete addition of the initiator the mixture is stirred for another 3 hours at 120° C.
  • Comparative example CEX2 corresponds to example 3 of US 2015/0376490 A1 .
  • Comparative example CEX3 corresponds to example 2 of US patent no. 7,345,010 .
  • Comparative example CEX4 corresponds to example 4 of US 2015/0376490 A1 .
  • Comparative example CEX5 corresponds to Thixatrol® DW50.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 79.3 g Dowanol PMA and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 37.4 g lauryl methacrylate, 29.2 g 2-ethylhexyl methacrylate, 12.7 g methacrylic acid and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 60.7 g Shellsol® A und heated up to 120° C under nitrogen atmosphere.
  • a mixture of 45.3 g lauryl methacrylate, 15 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 47.6 g Shellsol® A und heated up to 120° C under nitrogen atmosphere.
  • a mixture of 37.8 g butyl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 66.5 g Shellsol® A und heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 66.7 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 67.5 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 70.2 g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 70.2 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.27 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 66.8 g Amodrill® 1000 and 0.59 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 66.8 g Amodrill® 1000 and 0.295 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 67.2 g Amodrill® 1000 and 1.18 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 67.2 g Amodrill® 1000 and 0.88 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 68.0 g Amodrill® 1000 and 2.36 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 68.0 g Amodrill® 1000 and 1.77 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 71.5 g Amodrill® 1000 and 7.55 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 3.74 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 70.4 g Amodrill® 1000 and 3.78 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 1.87 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 57.0 g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 52.7 g lauryl methacrylate, 20.6 g 2-ethylhexyl methacrylate, 12.2 g 2-hydroxyethyl methacrylate and 0.48 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 57.0 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 52.7 g lauryl methacrylate, 20.6 g 2-ethylhexyl methacrylate, 12.2 g 2-hydroxyethyl methacrylate and 0.48 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 57.6 g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 52.7 g lauryl methacrylate, 20.6 g 2-ethylhexyl methacrylate, 6.1 g 2-hydroxyethyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.48 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 64.6 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 59.5 g lauryl methacrylate, 23.0 g 2-ethylhexyl methacrylate, 13.8 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 68.8 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 71.4 g lauryl methacrylate, 27.6 g 2-ethylhexyl methacrylate, 3.5 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 67.5 g Shellsol® A and 0.52 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 67.5 g Shellsol® A and 0.78 g 2,4-Diphenyl-4-methylpentene-1 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 47.6 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 37.8 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 40.3 g Shellsol® A and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 26.6 g methyl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 47.6 g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 37.8 g butyl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 6.9 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 27.8 g Amodrill® 1000 and 27.8 g 1-methoxy-2-propylacetate heated up to 120° C under nitrogen atmosphere.
  • a mixture of 60.4 g lauryl methacrylate, 22.7 g 2-ethylhexyl methacrylate, 11.5 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 70.2 g Amodrill® 1000 heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 60.7 g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 45.3 g lauryl methacrylate, 17.5 g 2-ethylhexyl methacrylate, 27.7 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 60.7 g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 60.9 g lauryl methacrylate, 23.8 g 2-ethylhexyl methacrylate, 3.1 g 2-(dimethylamino)ethyl methacrylate, 3.1 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 69.3 g Amodrill® 1000 and 3.8 g 2,4-diphenyl-4-methyl-1-pentene and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 67.7 g lauryl methacrylate, 26.2 g 2-ethylhexyl methacrylate, 5.7 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 55.6g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 60.4 g lauryl methacrylate, 22.7 g 2-ethylhexyl methacrylate, 11.5 g 2-hydroxyethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 62.9 g Amodrill 1000 and 3.8 g 2,4-diphenyl-4-methyl-1-pentene and heated up to 120° C under nitrogen atmosphere.
  • a mixture of 45.3 g lauryl methacrylate, 17.5 g 2-ethylhexyl methacrylate, 27.7 g 2-(dimethylamino)ethyl methacrylate and 0.54 g tert-butylperoxy-2-ethylhexyl carbonate is added by a dosing pump with a rate of 2.0 mL per minute.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 60.9 g Amodrill® 1000 and heated up to 120° C under nitrogen atmosphere.
  • the residual 5 wt.% of the mixture were mixed with 4.5 g tripropylene glycol diacrylate and were then added using the same rate. After one hour reaction time 0.24 g tert-butylperoxy-2-ethylhexyl carbonate is added. This procedure is repeated five times every 60 min. After the complete addition of the initiator the mixture is stirred for another 3 hours at 120° C.
  • the calculated amine number is 102 mg KOH/g.
  • a four-necked round-bottom flask equipped with stirrer, thermometer und reflux condenser is charged with 96.4 g dry THF and cooled down to 4° C under nitrogen atmosphere.
  • a mixture of 78.0 g butyl methacrylate and 54.4 g 2-ethylhexyl methacrylate is added by a dosing pump with a rate of 2.5 mL per minute.
  • 1.67 g 1-trimethylsiloxy-1-methoxy-2-methylpropene is added after the addition of 12.4 mL of the monomer mixture.
  • 0.17 g tetrabutylammonium chlorobenzoate is added. After finishing the monomer addition, the temperature is kept at 20 °C.
  • a four-necked round-bottom flask equipped with stirrer, thermometer and reflux condenser is charged with 96.4 g THF and cooled down to 4° C under nitrogen atmosphere.
  • a mixture of 78.0 g butyl methacrylate, 54.4 g 2-ethylhexyl methacrylate and 14.4 g 2-(dimethylamino)ethyl methacrylate is added by a dosing pump with a rate of 2.8 mL per minute. 1.67 g 1-Trimethylsiloxy-1-methoxy-2-methylpropene is added after the dosage of 13.6 mL of the monomer mixture.
  • An exemplary drilling fluid formulation comprising an oil phase with an emulsified water phase containing dissolved salts is disclosed hereinafter in Table 1 with concentrations reported in parts by weight (pbw).
  • Table 1 shows the components used, their amounts as well as how long to mix the components on the Silverson® mixer as further described hereinafter.
  • the components are mixed in the sequence as indicated by the entries in Table 1:
  • the oil based drilling formulation was prepared by first weighing the Amodrill® 1000 hydrocarbon product into a blending cup.
  • the additional components as indicated in "entries 2 to 8" of Table 1 were added and mixed sequentially according to Table 1 using a high shear mixer (Silverson® L4RT High Shear Mixer, Silverson Machines Inc., East Longmeadow, MA, USA).
  • the "rheological additive” corresponds to either one of comparative examples CEX1 to CEX7 or to one of inventive examples 1 to 35.
  • the "rheological additive” may in case additionally contain a fatty acid component, which is a dimeric or trimeric fatty acid, or a blend thereof.
  • drilling fluid formulations were aged at 150°F (65.5°C) for 16 hours to simulate real world conditions in a roller oven (OFITE 5-Roller Oven, OFI Testing Equipment Inc., Houston, TX, USA).
  • Yield point is a measurement of the attractive forces that cause the mud to resist flow. A proper yield point helps lift cuttings out of the annulus and reduce pressure changes that must be accounted for during the drilling process. A constant yield point across temperature changes increases drilling efficiency by preventing formation influx (i.e. the undesirable flow of formation fluid into the wellbore) and lost-circulation problems.
  • Gel strength is similar to yield point in causing a sudden pressure change at the start of pumping. However, the major difference between yield point and gel strength is that gel strength will not exist once the fluid is moving (i.e. after the gel has been broken). This contrasts yield point which effects will not disappear when the fluid is in motion. More specifically, gel strength defines the ability of the drilling mud to suspend drill solids and weighting materials when circulation ceases. To measure the gel strength, the viscometer is turned to 600 rpm for 15 seconds and quickly changed to 3 RPM before turning the instrument off for 10 seconds. After the allotted time the viscometer is turned back on and the highest peak reading is recorded as the 10 second gel strength (10"). This process is repeated, with an instrument rest time of 10 minutes, to record the 10 minute gel strength (10').
  • a flat rheological profile For a flat rheological profile, one skilled in the art identifies 6 RPM, 10 minute gel (10'), and yield point (YP) as the focus of drilling fluid rheological properties.
  • 6 RPM, 10' gel, and YP a system is considered to have a flat rheology profile when these values are within +/- 20% of the mean values across temperature ranges from 40° F to 150° F (4.4°C to 65.5°C). Lower percent variations for 6 RPM, 10' gel, and yield point indicate a flatter rheological profile. To best optimize the flat rheology profile, the 6 RPM, 10 minute gel, and yield point properties should all fall within these parameters.
  • viscosities are listed in readings (i.e., dial readings as defined in " Dictionary of Petroleum Exploration, Drilling & Production” by Norman Hyne, 2nd Edition, January 1991, published by PennWell Corp., Tulsa, Oklahoma, USA ), "gel” is measured in pounds per 100 square feet [lb/100 ft 2 ], “PV” is plastic viscosity and is measured in centipoise units [cP], “YP” is yield point and is measured in pounds per 100 square feet [lb/100 ft 2 ].
  • Drilling fluid DF7 (comparative, no rheological additive) Properties 40°F (4.4°C) 100°F (37.7°C) 150°F (65.5°C) 600 RPM reading 132 64 58 300 RPM reading 80 48 31 200 RPM reading 62 28 24 100 RPM reading 38 20 17 6 RPM reading 12 7 6 3 RPM reading 10 6 5 10" gel [lb/100 ft 2 ] 11 6 5 10' gel [lb/100 ft 2 ] 10 6 5 PV [cP] 52 16 27 YP [lb/100 ft 2 ] 28 32 4
  • Drilling fluid DF8 (comparative, only fatty acid component) Properties 40°F (4.4°C) 100°F (37.7°C) 150°F (65.5°C) 600 RPM reading 148 80 65 300 RPM reading 80 47 45 200 RPM reading 61 37 35 100 RPM reading 38 26 27 6 RPM reading 11 12 15 3 RPM reading] 10 11 13 10" gel [lb/
  • drilling fluids containing any of the inventive rheological additive DF1 to DF6 are able to produce a constant rheology across broad temperature changes (i.e. "flat rheology") in contrast to drilling fluids containing any of the comparative rheological additives DF9 to DF15.
  • inventive drilling fluids DF1 to DF6 that the amine and/or hydroxyl functional (meth)acrylic copolymer rheological additives primarily function by reducing temperature dependent rheological changes of the drilling fluid, most significantly by enhancing viscosity at higher temperatures and lower rotational frequencies.
  • Table 4 Flat Rheology comparison of additives in drilling fluid examples DF1 to DF6 and comparative Examples DF7 to DF15: Drilling fluid YP (Target: ⁇ 20%) 6 RPM (Target: ⁇ 20%) 10' Gel (Target: ⁇ 20%) DF7 54% 29% 29% DF8 31% 12% 4% DF1 18% 8% 7% DF2 18% 14% 4% DF3 15% 8% 6% DF4 17% 12% 3% DF5 17% 9% 3% DF6 19% 7% 2% DF9 103% 9% 7% DF10 31% 11% 5% DF11 31% 16% 8% DF12 26% 16% 8% DF13 23% 21% 2% DF14 124% 10% 5% DF15 104% 11% 4%
  • Percentages given in Table 4 represent mean percent changes from mean values at temperatures of 40°F (4.4°C), 100°F (37.7°C) and 150°F (65.5°C).
  • the dampening of the change in viscosity at higher rotational frequencies across temperature also had a dramatic impact on the yield point.
  • the addition of the inventive OH- and/or amino-functional (meth)acrylic copolymers decreased the mean percent change from mean values across temperature from 54% to values ranging from 15% - 19%. A significant drop off in 10' gel, from 29% to values ranging from 2% - 7% was also observed.
  • the non-functional (meth)acrylic copolymer (DF9) had a mean percent change from mean value of 103% for YP.
  • the two carboxyl functional (meth)acrylic copolymers (DF14 and DF15) had a mean percent change from mean value of 124% and 104% respectively for YP.
  • the inventive rheological additives outperformed the competitive flat rheology additives by reducing variations in 6 RPM readings and YP while maintaining a similar 10' gel strength. A minimal change in these rheological properties across temperature changes should be recognized by those of skill in the art as describing flat rheology.
  • the most significant improvement in rheology of the (meth)acrylic copolymer rheological additives relative to the comparative examples was a reduction in YP variation across temperature.
  • the comparative additives present in comparative drilling fluids DF10, DF11 and DF12 had a YP variation across 40°F (4.4°C), 100°F (37.7°C) and 150°F (65.5°C) temperature points ⁇ 26%, which is well above the variation reported for the inventive (meth)acrylic copolymers.
  • the comparative present in comparative drilling fluid DF13 had a slightly improved variation of 23%, but suffered from a significantly higher 6 RPM variation of 21%.
  • the commercial additive THIXATROL® DW 50 present in comparative DF13 had significantly higher 6 RPM and YP than the inventive (meth)acrylic copolymers contained herein.

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Claims (15)

  1. Bohrspülung in Form einer Wasser-in-Öl(W/O)-Emulsion, die mindestens Komponenten (A) bis (D), die jeweils voneinander verschieden sind, umfasst, und zwar
    (A) mindestens einen Kohlenwasserstoff als kontinuierliche Phase,
    (B) Wasser oder eine wässrige Lösung von mindestens einem organischen und/oder anorganischen Salz als diskontinuierliche Phase,
    (C) mindestens ein Beschwerungsmittel und
    (D) mindestens ein (Meth)acrylcopolymer,
    wobei das (Meth)acrylcopolymer (D) mindestens eine der voneinander verschiedenen Struktureinheiten (D1), (D2) und/oder (D3) enthält,
    wobei Struktureinheit (D1) mindestens eine Hydroxylgruppe umfasst und keine Aminogruppen umfasst,
    Struktureinheit (D2) mindestens eine Aminogruppe umfasst und keine Hydroxylgruppen umfasst und
    Struktureinheit (D3) sowohl mindestens eine Hydroxylgruppe als auch mindestens eine Aminogruppe umfasst
    und wobei das (Meth)acrylcopolymer (D) ferner mindestens eine Struktureinheit (D4) enthält, die von den Struktureinheiten (D1), (D2) und (D3) verschieden ist,
    wobei Struktureinheit (D4) die Teilstruktur (P) enthält
    Figure imgb0014
     wobei
    das Symbol
    Figure imgb0015
     für eine kovalente Bindung der Teilstruktur (P) zu dem Grundgerüst des (Meth)acrylcopolymers steht und R für einen aliphatischen C4-C25-Rest, einen aromatischen C6-C25-Rest oder einen araliphatischen C7-C25-Rest steht.
  2. Bohrspülung nach Anspruch 1, dadurch gekennzeichnet, dass das relative Molverhältnis von mindestens einer der Struktureinheiten (D1), (D2) und/oder (D3) zu der mindestens einen Struktureinheit (D4) in dem (Meth)acrylcopolymer im Bereich von 1:40 bis 1,5:1 liegt.
  3. Bohrspülung nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Menge an Struktureinheiten (D4) in dem (Meth)acrylcopolymer mindestens 40 mol-%, bezogen auf die Gesamtmenge aller Struktureinheiten des Copolymers, beträgt.
  4. Bohrspülung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass es sich bei der in den Struktureinheiten (D2) und/oder (D3) vorliegenden mindestens einen Aminogruppe um eine tertiäre Aminogruppe handelt.
  5. Bohrspülung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass Rest R für einen aliphatischen C4-C22-Rest oder einen aliphatischen C8-C18-Rest steht.
  6. Bohrspülung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass Komponente (D) des (Meth)acrylcopolymers durch Copolymerisation von mindestens einem der Monomere (d1), (d2) und/oder (d3) erhältlich ist, und zwar
    (d1) 3 bis 60 mol-% von mindestens einem ethylenisch ungesättigten Monomer mit mindestens einer Hydroxylgruppe oder mindestens einer funktionellen Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Hydroxylgruppe umgewandelt werden kann, und/oder
    (d2) 3 bis 60 mol-% von mindestens einem ethylenisch ungesättigten Monomer mit mindestens einer Aminogruppe oder mindestens einer funktionellen Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Aminogruppe umgewandelt werden kann, und/oder
    (d3) 3 bis 60 mol-% von mindestens einem ethylenisch ungesättigten Monomer mit mindestens einer Aminogruppe oder mindestens einer funktionellen Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Aminogruppe umgewandelt werden kann, und mit mindestens einer Hydroxylgruppe oder mindestens einer funktionellen Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Hydroxylgruppe umgewandelt werden kann,
    und mindestens einem der Monomere (d4), und zwar
    (d4) 40 bis 97 mol-% von mindestens einem aus der Gruppe bestehend aus (Meth)acrylestern eines aliphatischen C4-C25-Monoalkohols, (Meth)acrylestern eines aromatischen C6-C25-Monoalkohols, (Meth)acrylestern eines araliphatischen C7-C25-Monoalkohols und Mischungen davon ausgewählten Monomer
    sowie gegebenenfalls mindestens einem der Monomere (d5), (d6) und (d7), und zwar
    (d5) 0 bis 20 mol-% von mindestens einem aus der Gruppe bestehend aus (Meth)acrylestern eines aliphatischen C1-C3-Monoalkohols ausgewählten Monomer und/oder
    (d6) 0 bis 20 mol-% von mindestens einem Monomer mit genau einer ethylenisch ungesättigten Gruppe, das von jedem der Monomere (d1), (d2), (d3), (d4) und (d5) verschieden ist, und/oder
    (d7) 0 bis 5 mol-% von mindestens einem Monomer mit mindestens zwei ethylenisch ungesättigten Gruppen, das von jedem der Monomere (d1), (d2), (d3), (d4) und (d5) verschieden ist,
    wobei die Summe der für die Herstellung des Copolymers verwendeten Monomere (d1), (d2), (d3), (d4), (d5), (d6) und (d7) 100 mol-% ergibt.
  7. Bohrspülung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass Komponente (D) des (Meth)acrylcopolymers durch Copolymerisation von mindestens einem der Monomere (d1), (d2) und/oder (d3) erhältlich ist, und zwar
    (d1) 5 bis 50 mol-% von mindestens einem Monomer, das aus der Gruppe bestehend aus (Meth)acrylestern von aliphatischen C1-C6-Monoalkoholen, die mindestens eine Hydroxylgruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Hydroxylgruppe umgewandelt werden kann, tragen, (Meth)acrylamiden mit einer aliphatischen C1-C6-Gruppe, die mindestens eine Hydroxylgruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Hydroxylgruppe umgewandelt werden kann, tragen, und Mischungen davon ausgewählt ist, und/oder
    (d2) 5 bis 50 mol-% von mindestens einem Monomer, das aus der Gruppe bestehend aus (Meth)acrylestern von aliphatischen C1-C6-Monoalkoholen, die mindestens eine Aminogruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Aminogruppe umgewandelt werden kann, tragen, (Meth)acrylamiden mit einer aliphatischen C1-C6-Gruppe, die mindestens eine Aminogruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Aminogruppe umgewandelt werden kann, tragen, und Mischungen davon ausgewählt ist, und/oder
    (d3) 5 bis 50 mol-% von mindestens einem Monomer, das aus der Gruppe bestehend aus (Meth)acrylestern von aliphatischen C1-C6-Monoalkoholen, die mindestens eine Aminogruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Aminogruppe umgewandelt werden kann, und mindestens eine Hydroxylgruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Hydroxylgruppe umgewandelt werden kann, tragen, (Meth)acrylamiden mit einer aliphatischen C1-C6-Gruppe, die mindestens eine Aminogruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Aminogruppe umgewandelt werden kann, und mindestens eine Hydroxylgruppe oder mindestens eine funktionelle Gruppe, die nach der Bildung des Copolymers durch eine polymeranaloge Reaktion in eine Hydroxylgruppe umgewandelt werden kann, tragen, und Mischungen davon ausgewählt ist,
    und mindestens einem der Monomere (d4), und zwar
    (d4) 50 bis 95 mol-% von mindestens einem aus der Gruppe bestehend aus (Meth)acrylestern eines aliphatischen C4-C25-Monoalkohols, (Meth)acrylestern eines araliphatischen C7-C25-Monoalkohols und Mischungen davon ausgewählten Monomer,
    sowie gegebenenfalls mindestens einem der Monomere (d5), (d6) und (d7), und zwar
    (d5) 0 bis 15 mol-% von mindestens einem aus der Gruppe bestehend aus (Meth)acrylestern eines aliphatischen C1-C3-Monoalkohols ausgewählten Monomer und/oder
    (d6) 0 bis 15 mol-% von mindestens einem Monomer mit genau einer ethylenisch ungesättigten Gruppe, das von jedem der Monomere (d1), (d2), (d3), (d4) und (d5) verschieden ist, und/oder
    (d7) 0 bis 4 mol-% von mindestens einem Monomer mit mindestens zwei ethylenisch ungesättigten Gruppen, das von jedem der Monomere (d1), (d2), (d3), (d4) und (d5) verschieden ist,
    wobei die Summe der für die Herstellung des Copolymers verwendeten Monomere (d1), (d2), (d3), (d4), (d5), (d6) und (d7) 100 mol-% ergibt.
  8. Bohrspülung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass sie
    (A) Komponente (A) in einer Menge von 10 bis 60 Gew.-%,
    (B) Komponente (B) in einer Menge von 2,5 bis 40 Gew.-%,
    (C) Komponente (C) in einer Menge von 10 bis 90 Gew.-% und
    (D) Komponente (D) in einer Menge von 0,005 bis 8 Gew.-%,
    jeweils bezogen auf das Gesamtgewicht der Bohrspülung, umfasst, wobei die Gesamtmenge aller in der Bohrspülung vorliegenden Komponenten 100 Gew.-% ergibt.
  9. Bohrspülung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass sie ferner mindestens eine organische Säure als Komponente (E) umfasst.
  10. Bohrspülung nach Anspruch 9, dadurch gekennzeichnet, dass es sich bei der als Komponente (E) verwendeten mindestens einen organischen Säure um mindestens ein Oligomer von mindestens einer C10-C28-Fettsäure handelt und dass das relative Gewichtsverhältnis von dem (Meth)acrylcopolymer zu dem mindestens einen Oligomer der mindestens einen C10-C28-Fettsäure im Bereich von 1:9 bis 9:1 liegt.
  11. Bohrspülung nach Anspruch 9 oder 10, dadurch gekennzeichnet, dass sie
    (E) Komponente (E) in einer Menge von 0,01 bis 5 Gew.-%,
    bezogen auf das Gesamtgewicht der Bohrspülung, umfasst, wobei die Gesamtmenge aller in der Bohrspülung vorliegenden Komponenten 100 Gew.-% ergibt.
  12. Bohrspülung nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass sie mindestens ein weiteres Additiv enthält, das aus der Gruppe bestehend aus Thixotropiermitteln, Emulgatoren, Alkalinität verleihenden Komponenten, Stützmitteln, Additiven gegen Spülungsverlust, Verdünnern und Verdickungsmitteln ausgewählt ist.
  13. Verwendung von mindestens einem (Meth)acrylcopolymer als rheologisches Additiv in einer Bohrspülung, wobei es sich bei der Bohrspülung um eine Wasser-in-Öl(W/O)-Emulsion handelt und wobei das (Meth)acrylcopolymer mindestens eine der voneinander verschiedenen Struktureinheiten (D1), (D2) und/oder (D3) enthält,
    wobei Struktureinheit (D1) mindestens eine Hydroxylgruppe umfasst und keine Aminogruppen umfasst,
    Struktureinheit (D2) mindestens eine Aminogruppe umfasst und keine Hydroxylgruppen umfasst und
    Struktureinheit (D3) sowohl mindestens eine Hydroxylgruppe als auch mindestens eine Aminogruppe umfasst
    und wobei das (Meth)acrylcopolymer ferner mindestens eine Struktureinheit (D4) enthält, die von den Struktureinheiten (D1), (D2) und (D3) verschieden ist,
    wobei Struktureinheit (D4) die Teilstruktur (P) enthält
    Figure imgb0016
     wobei
    das Symbol
    Figure imgb0017
     für eine kovalente Bindung der Teilstruktur (P) zu dem Grundgerüst des (Meth)acrylcopolymers steht und
    R für einen aliphatischen C4-C25-Rest, einen aromatischen C6-C25-Rest oder einen araliphatischen C7-C25-Rest steht.
  14. Verwendung nach Anspruch 13, dadurch gekennzeichnet, dass das mindestens eine (Meth)acrylcopolymer als rheologisches Additiv in Kombination mit mindestens einer organischen Säure verwendet wird.
  15. Verfahren zur Förderung von Öl und/oder Erdgas oder zur Vorbereitung der Förderung von Öl und/oder Erdgas, umfassend den Schritt des Verwendens einer Bohrspülung nach einem der Ansprüche 1 bis 12 zur Erzeugung und/oder zum Betrieb einer Bohrung.
EP17822237.8A 2017-01-03 2017-12-14 (meth)acrylatcopolymere als rheologische additive in bohrflüssigkeiten und bohrflüssigkeiten mit solchen copolymeren Active EP3565865B1 (de)

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